NETTERSHEIM, Germany Concealed in a thicket of brambles in hills southwest of Cologne, out of sight of the nearby motorway, an eerie relic of Germany's Nazi past has been neglected for over 60 years.
Under layers of dead wood and leaves lies part of Hitler's "Westwall" -- the "Siegfried Line" as it is known in English -- a 630 km (390 mile) defensive line of bunkers and anti-aircraft defences that once ran the length of Germany's western border.
The concrete fortifications have lain untended for decades and are now covered in moss. Birds nest in cracks in the bullet-scarred walls, and bats and wild cats snooze in the darkest corners.
But in the last few years, some locals in the Eifel region have tried to stop bulldozers annihilating this reminder of the grimmest period of German history.
"It's important to keep the bunkers as a reminder for future generations, and also to preserve the wildlife," said Sebastian Schoene, head of a project for the BUND nature conservation body in North Rhine-Westphalia state, which still has 2,000 bunkers.
"But doing this sort of thing in Germany is very sensitive."
Some people want to convert a few of the fortifications -- which stretched from Kleve on the Dutch border to near Basle in Switzerland -- into museums.
The dilemma over the remains of the Siegfried Line echoes debates about what to do with other major monuments of the Nazi era in Germany: a fear of airbrushing away Nazi crimes competes with an almost equal fear of glorifying them.
It is only recently that exhibitions have opened at some well-known Nazi sites, such as Hitler's "Berghof" mountain retreat in Bavaria and his rallying ground in Nuremberg. The Berlin bunker where he committed suicide remains sealed and inaccessible.
Hitler ordered the building of the Siegfried Line, consisting of 17,000 bunkers, between 1936 and 1940 to shield Germany's western flank while he sent millions of troops east.
"The unbreachable fortification in the West", as newspapers at the time described it, spawned a major propaganda campaign.
Its construction provided work for hundreds of thousands and was even filmed to boost morale in the Third Reich.
"They created a myth out of it, they wanted to show it was stronger than any other fortification," said Peter Drespa, who has helped open the Westwall Centre at Dahlem, which attracts American and British tourists.
"We are not glorifying the bunkers ... We are in fact showing how the Third Reich did not function. We need to expose the myth," said Drespa.
Many historians say the line's propaganda value surpassed its practical worth as no attack came from the West -- at least not until after the Allies landed in Normandy in 1944.
"By the time the Americans got there in September 1944, the installations had been weakened and German soldiers ended up only occupying about a fifth of the bunkers," said Drespa.
The Eifel's gentle hills and dark forests then witnessed some fierce battles.
At Huertgenwald near Aachen -- an area of narrow wooded valleys -- an estimated 12,000-15,000 Germans and at least 35,000 U.S. soldiers lost their lives before and during the Wehrmacht's "Battle of the Bulge" offensive.
After 1945 the Allies blew up most of the bunkers, leaving them as ruins.
There has never been a national strategy for the defences and the government, worried about public safety and lobbied by farmers keen to use the land, has gradually destroyed them.
A few determined individuals such as Drespa were left to fight the bureaucracy and organize the funding to preserve the bunkers. A handful have succeeded.
Thanks to BUND's campaign, no bunkers have been destroyed in North Rhine-Westphalia state for two years. The group has received verbal assurances the moratorium will be made permanent -- but in other states, the bulldozers are still at work.
"The bunkers have developed into islands of wildlife in the last 60 years. They are a valuable retreat for wild animals and authorities are breaking the law if they destroy the habitat of protected species like wild cats and rare bats," said Schoene.
The damp atmosphere and the decaying concrete provide ideal conditions for trees and rare mosses as well as for grass snakes and a multitude of insects, song birds and owls.
The fact that Schoene's priority is saving wildlife brings accusations that he is ignoring history:
"Some people say our project is an attempt to sanitize the bunkers and make them sound pretty. I thought things would change with a new generation -- but people still have the same views, and it's tiring having these arguments."